This Guide outlines the essential characteristics of reference materials for quality control (QC) purposes, and describes the processes by which they can be prepared by competent staff within the facility in which they will be used (i.e. where instability due to transportation conditions is avoided). The content of this Guide also applies to inherently stable materials, which can be transported to other locations without risk of any significant change in the property values of interest.

The primary audience for this Guide is laboratory staff who are required to prepare and use materials for specific in-house quality control applications. Preparation of QCMs, where transportation is a necessary component of the supply chain, such as laboratory sites at different locations or for proficiency testing schemes, should conform to the relevant requirements of ISO Guides 34^[1] and 35.^[2]

The description of the production of reference materials (RMs), as detailed in ISO Guide 34^[1] and ISO Guide 35^[2] is also applicable to the preparation of quality control materials (QCMs). However, the requirements for “in-house” QCMs are less demanding than those for a certified reference material (CRM). The preparation of QCMs should involve homogeneity and stability assessments, and a limited characterization of the material to provide an indication of its relevant property values and their variation, prior to use. This document provides the quality criteria that a material should fulfil to be considered fit-for-purpose for demonstrating a measurement system is under statistical control. Guidance on uses of such materials, for example setting up a QC chart, is adequately covered elsewhere ^{[3],[4],[5],[6]} and is not included in this Guide.

The layout and structure of this Guide provides general information on the preparation of QCMs in the main chapters, with specific case studies covering a range of sectors in the annexes. The case studies are not complete “process manuals” but are included to highlight some of the key considerations when preparing QCMs. The case studies vary in complexity and detail, including sector specific terminology, but provide a range of information for laboratory staff to draw from.

It is expected that those involved in QCM preparation will have some knowledge of the type of material to be prepared and be aware of any potential problems due to matrix effects, contamination, etc.